A subterranean formation surrounding a well may be fractured to improve communication of fluids through the formation, for example, to/from the well. The fracturing is often performed in stages, where a segment or interval of the well is fractured, the interval is sealed off, and then a subsequent interval fractured. The intervals are sealed by setting a plug that seals the bore of the well below a certain depth or by shifting a frac sleeve that seals the perimeter of the well from communication with the surrounding formation. The frac sleeves are typically shifted using various sized frac balls, collets or other similar devices dropped from the surface into the well as the fracturing fluid is pumped. The ball, collet or other device lands on a corresponding profile of the sleeve and causes it to shift close. Also, in completion and workover operations, tools are extended into the well under pressure on wireline or coiled tubing to perform various operations, such as perforating the well casing.
Like reference symbols in the various drawings indicate like elements.